The invention relates to ink jet printing devices and more particularly to ink jet cartridges having replaceable ink tanks with internal filters for use in ink jet printers. The cartridges are mounted on translatable carriages in the ink jet printers for translation thereby during the printing mode.
Existing ink jet printing devices typically rely on some form of filtration, but generally have a filter that is included as part of the printhead mechanism or, in the case of disposable ink jet cartridges which integrate the ink supply tank and printhead, the filter is generally located between the printhead ink inlet and the ink supply tank outlet. In either case, the filter is used without replacement until the printhead or cartridge is removed and discarded. It is well known that ink tanks using foam or felt as an ink holding and dispensing medium contaminate the ink with dislodged fibers and particles. These contaminates delivered from the ink tank range in sizes that can cause the filters used to protect the printhead to become clogged over time during use and can cause immediate or long term ink jet printhead performance degradation. Such contaminants have been known to substantially block the filter and prevent ink droplet ejection from some of the nozzles, which is sometimes referred to as ink jet dropout.
In drop-on-demand, liquid ink printing devices, power pulses are used to selectively eject ink droplets from printhead nozzles to confronting recording mediums, such as paper. Such printing devices may either use piezoelectric, acoustic, or thermal droplet ejectors to expel ink droplets. In the thermal ink jet printing devices, the power pulses are usually produced by resistors located in channels which are selectively addressed with electric pulses to heat rapidly and momentarily vaporize ink in the channels. As voltage is applied across a selected resistor, an ink vapor bubble grows and causes the ink to bulge from channel nozzles. Removal of the voltage from the resistor causes the vapor bubble to collapse quickly and the ink in the channel to retract towards the collapsing bubble, thereby separating the bulging ink and producing a droplet which is propelled from the nozzle towards a recording medium. When the droplet impacts on the recording medium, a dot or spot is deposited. The channel is refilled by capillary action and ink is withdrawn from a supply container or cartridge. The operation of a typical thermal ink jet printer is described, for example, in U.S. Pat. No. 4,849,774.
The carriage type ink jet printer typically has one or more small printheads containing the ink channels and nozzles. The printheads are combined with ink supply tanks to form an ink cartridge. In one type of cartridge, the printhead and one or more ink tanks are an integral part thereof and the entire cartridge is disposable when the ink in the tanks is depleted. In another type of cartridge, such as disclosed, for example, in U.S. patent application Ser. Nos. 08/668,802 filed Jun. 24, 1996, entitled "Ink Supply Container With Improved Foam Retention Properties", and 08/820,624, filed Mar. 19, 1997, entitled "Ink Jet Printer Including A Disengageable Medium Transport For Jam Clearance", the printheads are an integral part thereof with the ink supply tanks for the cartridge being replaceable. Cartridges which have replaceable ink supply tanks may also be replaceable, but are designed for a life expectancy of at least ten ink supply tanks. If the cartridge for replaceable ink supply tanks is a multicolor type, then the replaceable cartridge should not need to be replaced until at least ten ink supply tanks of the same color ink are depleted of ink. The ink supply tanks are mounted on the cartridge and sealingly connected to integral ink connectors of the cartridge which are covered by permanent filters. Both types of cartridges are mounted on a translatable carriage in the printer and translated in one direction to print a swath of information on a recording medium, such as paper. The swath height is equal to the length of the column of nozzles in the printhead. The paper is held stationary during the printing and, after the swath is printed, the paper is stepped a distance equal to the height of the printed swath or a portion thereof. This procedure is repeated until the entire page is printed. The filters for each of these types of cartridges are used for the entire life of the printhead, as contrasted with the present invention where the filters are fresh with each new ink supply tank.
U.S. Pat. No. 4,771,295 discloses an ink supply cartridge construction having multiple ink storage compartments. Ink is stored in a medium of reticulated polyurethane foam of controlled porosity and capillarity. The medium empties into ink pipes, the entrances of which are provided with wire mesh filters for filtering of air bubbles and solid particles from the ink. The ink in the ink pipes is directed to the printheads which are permanently attached to the cartridge. The entire cartridge is replaced when the ink has been depleted therefrom.
U.S. Pat. No. 5,519,425 and U.S. Pat. No. 5,491,501 disclose disposable ink cartridges in which the printheads and ink tanks are integrally attached. The ink is contained in an absorbent material in a housing which is partitioned from the printhead by a housing wall having a vent and an ink outlet in a well which is covered by a filter. The ink flow path is from the absorbent material through the filter into the well and out the ink outlet into a passageway which is in fluid communication with the printhead.
U.S. Pat. No. 5,204,690; U.S. Pat. No. 5,124,717; and U.S. Pat. No. 5,141,596 disclose an ink jet printhead having a filter at the ink inlet of the printhead which is an integral part of the printhead.
As disclosed above and in conventional ink jet cartridges, ink filtration is generally included as a permanent part of the printhead or cartridges having the printheads permanently attached thereto. Thus, the filters must be suitably functional for the life of the printhead. However, the absorbent material used in the typical ink cartridges tends to deteriorate or otherwise give off particles or debris which is collected by the filters, along with all other ink contaminants, so that with use the filters are progressively clogged. This clogging of the filter results in the ink flow to the printhead channels being impeded or blocked, which prevents the cartridge and/or printhead from achieving its normal usage or lifetime.